1. Field of the invention
This invention relates to an improved outer shell for a fire-resistant garment, such as a firefighter protective garment. More particularly, the present invention is concerned with a laminated outer shell made of plain multifilament woven fabric and another textile or non textile material, which is non slipping and non fraying and is more resistant than those made from a twill fabric or has a better air permeability than those which are coated with an antislip finish. The air permeability must be of at leat ten (10) cubic feet per minute (CFM), when tested in accordance with ASTM D737.
2. Description of Prior Art
Firefighter protective garments usually consist of three or more discrete layers of fire-resistant materials. The various layers are normally:
1) the outer shell which provides protection against puncture, cuts, flame and heat;
2) the moisture barrier substrate and moisture barrier polymer which, although fire-resistant, have as their principal purpose protection against liquid penetration (in certain cases they are permeable to perspiration vapor to increase wearer comfort);
3) the thermal barrier insulation whose principal function is to provide protection against heat transfer; and
4) the inner lining or face cloth (which is normally quilted to the thermal barrier insulation) which protects the thermal barrier from wear from the inside of the garment, and provides a last layer of heat and flame protection.
An outer shell of good quality does not slip or fray. Slipping occurs when yarns of one direction, e.g. warp, are displaced laterally with respect to the yarns in the other direction, e.g. fill. Fraying occurs when yarns separate from the fabric matrix at the exposed edges of fabric weave.
Slipping and fraying are common to multifilament fabrics.
Slipping and fraying in non-fire resistant fabrics of multifilamentary yarns can be controlled by heat setting. However, the inherently fire-resistant properties of the multifilamentary yarns composing many fire-resistant fabrics render heat setting ineffective.
One method of overcoming slippage and fraying of fabrics consisting of multifilamentary yarns is to introduce a certain proportion of spun yarns into either the warp direction, the fill direction or both warp and fill directions of the fabric weave. However, the differences in chemical and fire-resistant properties between the multifilamentary and spun yarns may create a fabric that does not have the desired performance characteristics.
Another method for overcoming slippage and fraying consists of a coating or laminated film on one or both surfaces of the fabric to immobilize the yarns with respect to one another. However, this method reduces the air permeability of the fabric and may render a garment made of the fabric less comfortable.
It is an object of the present invention to provide an outer shell for a firefighter garment which is free of slippage and fraying and which is also permeable to air.
It is another object of the present invention to provide an outer shell for a fire-resistant garment which maximizes the insulation value to weight ratio of the garment.
Outer shells for fire-resistant garments are disclosed in the following U.S. Pat. Nos.:
4,188,445
4,255,817
4,937,136
5,007,112
5,014,357
5,050,241
5,136,723.
However, none of these references teach a product which combines maximum insulation with reduced slippage and fraying.